Metastasizing myxopapillary ependymoma of the sacrococcygeal region. A clinico-pathologic, light- and electronmicroscopic, immunohistochemical, tissue culture, and cytogenetic analysis of a case.

A case of recurrent and metastasizing subcutaneous myxopapillary ependymoma of the sacrococcygeal region in a 44-year-old man is reported. The tumor was characterized light microscopically by numerous papillary projections, lined by epithelium-like cells, with a variable degree of polymorphism. Histochemical analysis relating to glucosaminoglycans indicated the presence of hyaluronic acid and chondroitin-4- and/or 6-sulfate. Using immunoperoxidase techniques, glial fibrillary acidic protein (GFAP) and S-100 protein were demonstrated within the tumor cells. Ultrastructurally, the tumor cells were characterized by an abundance of intermediate cytoplasmic filaments, prominent interdigitating cytoplasmic projections, the formation of desmosomes and external lamina-like material. The growth pattern in the tissue culture of this tumor is described, and the ultrastructural appearance of the cultured cells revealed features similar to the primary and recurrent tumor. Chromosome analyses by the G-banding technique of early generations of cultured tumor cells revealed a normal diploid stemline without gross chromosomal deviations. Among the different variant cells and clones recorded, those with X chromosome deviations were of special interest since gonosomal deviations have previously been observed in other types of glioma. The differential diagnosis against adenopapillary carcinoma, chordoma and malignant teratoma is briefly discussed.